PC Magazine reviewed and ranked cleaning tools, free AV projects, and premium suites in the attached article:
AntiVirus Products for 2012 – Review by PC Magazine
QUOTE: To evaluate antivirus utilities I rely on hands-on, real-world testing. The malware removal test involves installing each product on a dozen malware-infested virtual machines and challenging it to clean them up. This article explains how I get from those tests to the figures in the chart below: How We Test Malware Removal I also refer to reports from major independent antivirus testing labs. The labs have vastly more resources than I do, so they can perform large-scale tests that would take more time than I have available. The chart below specifically lists results for the companies whose 2012 products are rounded up here.
PC Magazine shares an recent review of MSE 4.0 … In personal testing on all family PCs, there is more consistency in auto-updating and it continues to be transparent in terms of impacting performance. No issues so far in use on XP and Windows 7 systems.
Microsoft Security Essentials 4.0
QUOTE: This product is a straight-up antivirus, not a feature-stuffed suite wannabe. Its main window shows current security status, with a button to resolve any problems. Another button launches an on-demand scan. That’s it!
Pros — Does a decent job protecting an already-clean system. Good ratings from independent antivirus test labs. Free!
Cons — Unusually slow scan. Failed to run on one test system. Low detection rate in malware cleanup test. Failed to thoroughly clean up threats it did detect.
Bottom Line — Microsoft Security Essentials 4.0 does a decent job protecting a clean PC, but in testing its cleanup of already-infested systems wasn’t thorough.